During the average regular season, Rivera pitches in 37% of the Yankees' game. In the postseason he pitches in 60% of them.

Since 1996 (to exclude the time in 1995 he spent as a starting pitcher), he's averaged 1.15 innings per appearance. Starting in 1997, when he became a closer, it's been 1.10 innings per appearance. In the postseason Rivera averages 1.55 innings per appearance.

Clearly the extra work hasn't negatively impacted him during the month of October, as he has a 0.81 ERA in 153% of a normal season's worth of innings.

This is one of the large ways (along with the more obvious use of backups and pitching rotations) the postseason, and the days off in the postseason, makes it a different ballgame than the regular season.

Of course the Yankees learned last seasons that in a 5-game series, if they can only get the ball to Rivera twice, his impact isn't nearly as relevant. They needed him in his usual 60%.